Solution‐processable transmissive‐to‐green switching electrochromic polyamides bearing 2,7‐bis(diphenylamino)naphthalene units

A new 2,7‐bis(diphenylamino)naphthalene‐based diamine monomer, N,N′‐bis(4‐aminophenyl)‐N,N′‐bis(4‐methoxyphenyl)‐2,7‐naphthalenediamine, was synthesized and polymerized with various aromatic dicarboxylic acids via the phosphorylation polyamidation reaction leading to a new series of redox‐active and electrochromic aromatic polyamides. The polyamides exhibited high solubility in many polar aprotic solvents, good film‐forming ability, and high thermal stability. They also showed stable electrochemical stability and anodically green coloring when oxidized. The two arylamino centers showed a weak electronic interaction via the 2,7‐naphthalenediyl bridge, and thus they started to oxidize almost at the same time. No intervalence charge transfer (IVCT) absorption was observed during the oxidation processes of these polyamides. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1409–1421     

Enhancing the electrochromic characteristics of conjugated polymer with TiO2 nano‐rods

Organic soluble, oleic acid capped TiO₂ nano‐rod was well‐mixed with the electrochromic polymer: Poly‐(4,4‐dioctylcyclopenta[2,1‐b:3,4‐b′]‐dithiophene (PDOCPDT) to form TiO₂/PDOCPDT nanocompsoite. TiO₂/PDOCPDT film showed high electrochemical stability and its coloration efficiency is 1.5 times of that for pure PDOCPDT. The function of TiO₂ nano‐rods can be regarded as a dispersion agent. PDOCPDT chains in TiO₂/PDOCPDT may have a less aggregated structure and more open morphology, therefore has higher coloration efficiency. TiO₂ may also act as electron transport or temporary electron storage centers, electrons can be transferred reversibly between PDOCPDT and TiO₂ nano‐rods. TiO₂/PDOCPDT is well‐soluble in CHCl₃, large area thin films can be fabricated reproducibly simply by spin coating. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1121–1130, 2008     

A comparative study of gold nanocubes, octahedra, and rhombic dodecahedra as highly sensitive SERS substrates

Gold nanocubes, octahedra, and rhombic dodecahedra with roughly two sets of particle sizes have been successfully synthesized via a seed-mediated growth approach. All six samples were analyzed for comparative surface-enhanced Raman scattering (SERS) activity. All of these Au nanostructures were found to yield strong enhancement at a thiophenol concentration of 10(-7) M and are excellent SERS substrates. Rhombic dodecahedra with a rhombus edge length of 32 nm showed significantly better enhancement than the other samples and can reach a detection limit of 10(-8) M. Simulations of the binding energies of thiophenol on the different faces of gold and electric near-field intensities of these nanocrystals have been performed to evaluate the experimental results. Superior SERS activity of these nanocrystals can be expected toward the detection of many other molecules.     

Determination of Polybrominated Diphenyl Ethers in Coastal and River Sediments by Pressurized Liquid Extraction Coupled with Gas Chromatography‐Mass Spectrometry

This study presents a time‐ and solvent‐saving method, pressurized liquid extraction (PLE), to extract polybrominated diphenyl ethers (PBDEs) in sediment samples. The effects of various operating parameters (i.e., extraction solution, temperature, pressure, static/dynamic extraction times) for the quantitative extraction of PBDEs by home‐made PLE were systematically investigated and optimized. The analytes were then identified and quantitated by gas chromatography‐mass spectrometry (GC‐MS) in selected ion monitoring (SIM) mode. The 16 PBDE congeners (from tri‐ to deca‐BDE) can be completely extracted by dichloromethane: n‐hexane (3/2, v/v) at 100 °C and 100 atm combined with 15 min static and then 15 min dynamic extraction steps. Recovery of PBDEs in spiked sediment samples ranged from 52 to 104% with 2‐16% RSD, except for BDE‐206. Limits of quantitation (LOQ) were established between 4 and 400 pg/g (dry weight) in 10 g of sediment sample. The extraction efficiency of the PLE was also compared with the traditional Soxhlet extraction method. The total contents of PBDEs ranged from 8.0 to 37.9 ng/g (dry weight) in various river and coastal sediment samples in Taiwan. Deca‐BDE (BDE‐209) was the major PBDE detected in these sediment samples.     

Insight into the electrochemical reduction of CO2 on gold via surface-enhanced Raman spectroscopy and N-containing additives

Journal of Solid State Electrochemistry - Due to increasing levels of greenhouse gases in the atmosphere, increased attention has been given to minimizing their emissions and reducing current...     

Global attractors for the discrete Klein–Gordon–Schrödinger type equations

The purpose of this work is to investigate the asymptotic behaviours of solutions for the discrete Klein–Gordon–Schrödinger type equations in one-dimensional lattice. We first establish the global existence and uniqueness of solutions for the corresponding Cauchy problem. According to the solution's estimate, it is shown that the semi-group generated by the solution is continuous and possesses an absorbing set. Using truncation technique, we show that there exists a global attractor for the semi-group. Finally, we extend the criteria of Zhou et al. [S. Zhou, C. Zhao, and Y. Wang, Finite dimensionality and upper semicontinuity of compact kernel sections of non-autonomous lattice systems, Discrete Contin. Dyn. Syst. A 21 (2008), pp. 1259–1277.] for finite fractal dimension of a family of compact subsets in a Hilbert space to obtain an upper bound of fractal dimension for the global attractor.     

A Pentacyclic Nitrogen‐Bridged Thienyl–Phenylene–Thienyl Arene for Donor–Acceptor Copolymers: Synthesis,Characterization, and Applications in Field‐Effect Transistors and Polymer Solar Cells

A pentacyclic benzodipyrrolothiophene ( BDPT ) unit, in which two outer thiophene rings are covalently fastened with the central phenylene ring by nitrogen bridges, was synthesized. The two pyrrole units embedded in BDPT were constructed by using one‐pot palladium‐catalyzed amination. The coplanar stannylated Sn‐BDPT building block was copolymerized with electron‐deficient thieno[3,4‐c]pyrrole‐4,6‐dione ( TPD ), benzothiadiazole ( BT ), and dithienyl‐diketopyrrolopyrrole ( DPP ) acceptors by Stille polymerization. The bridging nitrogen atoms make the BDPT motif highly electron‐abundant and structurally coplanar, which allows for tailoring the optical and electronic properties of the resultant polymers. Strong photoinduced charge‐transfer with significant band‐broadening in the solid state and relatively higher oxidation potential are characteristic of the BDPT‐based polymers. Poly(benzodipyrrolothiophene‐alt‐benzothiadiazole) ( PBDPTBT ) achieved the highest field‐effect hole mobility of up to 0.02 cm² V^?1 s^?1. The photovoltaic device using the PBDPTBT /PC₇₁BM blend (1:3, w/w) exhibited a V_oc of 0.6 V, a J_sc of 10.34 mA cm^?2, and a FF of 50 %, leading to a decent PCE of 3.08 %. Encouragingly, the device incorporating poly(benzodipyrrolothiophene‐alt‐thienopyrrolodione) ( PBDPTTPD )/PC₇₁BM (1:3, w/w) composite delivered a highest PCE of 3.72 %. The enhanced performance arises from the lower‐lying HOMO value of PBDPTTPD to yield a higher V_oc of 0.72 V.     

Synthesis and anti‐inflammatory effect of morachalcone B,morachalcone C,and analogs

An efficient method to synthesize morachalcones B and C ( 1 and 2 ) is described. Rap?Stoermer condensation and 1,3‐prenyl rearrangement were used as two key synthetic methods. Morachalcone C was obtained by photo‐oxygenation of morachalcone B. Morachalcones B and C showed moderate anti‐inflammatory activity.     

Kinetic and mechanistic studies of NEt3-catalyzed intramolecular aminolysis of carbamate

The mechanism of the NEt 3-catalyzed intramolecular aminolysis of Z- 1 in acetonitrile or aqueous acetonitrile solutions is suggested to involve rate-determining collapse of T (+/-) through simultaneous H-abstraction and ethoxide expulsion of E2 process. The evidence for that includes the primary isotope effect of k H/ k D = 1.66 in acetonitrile, general-base catalysis in aqueous buffer solutions, salt effect, and the proposed water-stabilized rate-determining transition states (TS1 and TS2) in the water-titration experiments.